After you click the poll icon, click submit and it will take you to another page for poll options such as the poll question, how many opinions(up to 5), if you want the poll to be public or private and if you want people to vote more than once.

My two scents,
If you have already posted the topic you can clikc on Thread Tools in the right upper hand corner and create a poll for the topic at hand. However, I believe only the orginial poster/creator and mods can do this.